1. Field of the Invention
The described invention relates generally to the field of computer systems. More particularly, this described invention relates to a high speed display system that allows command and display data to be transmitted between the display monitor and a computer system through a single cable.
2. Description of Art Related to the Invention
In recent years, integrated circuit microcontrollers have become less expensive, thereby increasing their use in a variety of systems including display monitors used in conjunction with computer systems. A microcontroller, placed in such a display monitor, generally controls various parameters of the display monitor (e.g., power, brightness, screen configuration, etc.) through command data. The command data for controlling the microcontroller is usually generated by software stored external to the display monitor such as within a computer system.
One method for transferring command data to a microcontroller employed within a display monitor includes the use of a control data cable coupling the display monitor and the computer system. The control data cable enables command data to be transmitted under a standard asynchronous serial communication method from the computer system to the display monitor. As a result, various software programs running on the computer system may be used to automatically configure the display monitor through the transmission of certain commands. Thus, unnecessary costs associated with mechanical controls (knobs, switches and the like) may be eliminated.
In conventional computer systems, in addition to the control data cable, a display data cable is coupled between the computer system and the display monitor in order to transfer display data. The display monitor uses the display data to generate an image on a display screen. Utilizing both a control data cable and a display data cable, however, has a number of disadvantages.
One disadvantage is that multiple cables increase the overall cost of the computer system by requiring more connections and additional components. Moreover, it is often necessary to install an extra serial communication card in the computer system so that it may transmit the commands to the display monitor, thereby causing further costs to be incurred.
Another disadvantage is that multiple cables provide difficulties in controlling EMI radiation, contrary to a single cable implementation whereby EMI radiation can be controlled quite easily and inexpensively. In addition, multiple cables complicate the set-up of the computer system and cause unwanted clutter surrounding the computer system. Based on the foregoing and any other disadvantages, it is desirable to have a method and apparatus for interfacing a computer system to a display monitor that transmits both command data and display data through a single monitor interface cable.
A method and apparatus for transmitting display data and command data between a computer system and a display monitor having a microcontroller is described. A monitor interface cable is provided in which both display and command data are transmitted simultaneously from the computer system to the display monitor. Inside the computer system, command data written to a particular memory location within a video buffer card is applied to various signal lines located in the monitor interface cable. These signal lines are coupled to the microcontroller, located in the display monitor, which receives the command data and performs various controlling functions in response. Status information is transmitted back across a second signal line to the computer system where various software programs including drivers receive and process the status information. Display data is simultaneously transmitted with the command data over other signal lines located in the monitor interface cable enabling the display monitor to show various images on a display screen.